This is a Phase III, randomised, assessor-blind, parallel group, multicentre trial. At least 180 adult subjects with high-risk Stage II or Stage III / IV breast cancer will be randomised (1:1) to receive either Eurofarma's pegfilgrastim (n = 90) or Neulastim (n = 90) in 8 to 10 sites in Brazil. Subjects will undergo a maximum of 4 cycles of myelosuppressive chemotherapy (21 days per cycle).